title: Effects of chemical restraint on electroretinograms recorded sequentially in awake, sedated, and anesthetized dogs.
abstract: OBJECTIVE
  To quantitatively and qualitatively compare electroretinography (ERG) recordings in awake, sedated, and anesthetized dogs.
  
  
  METHODS
  Six 6-month-old Beagles.
  
  
  METHODS
  A brief ERG protocol for dogs was used. Following 1-minute and subsequent 5-minute dark adaptation, mixed rod-cone responses were recorded bilaterally with a handheld multispecies ERG device with dogs in each of 3 states of consciousness: awake, sedated (dexmedetomidine and butorphanol), and anesthetized (atropine and hydromorphone, followed by propofol and midazolam and anesthetic maintenance with isoflurane). Low- and high-frequency noise levels were quantified via Fourier analysis, and the effect of consciousness state on signal amplitude, implicit time, and noise was analyzed via repeated-measures ANOVA. In addition, 13 veterinary ophthalmologists who were unaware of the dogs' consciousness states subjectively graded the ERG recording quality, and scores for each tracing were compared.
  
  
  RESULTS
  ERG amplitudes were highest in awake dogs and lowest in anesthetized dogs. Implicit times were shortest in awake dogs and longest in anesthetized dogs. Differences in b-wave amplitudes and a-wave implicit times were significant. Neither low- nor high-frequency noise levels differed significantly among consciousness states. Furthermore, no significant differences were identified among observers' scores assigned to ERG tracings.
  
  
  CONCLUSIONS
  Anesthesia and sedation resulted in significant attenuation and delay of ERG responses in dogs. Chemical restraint of dogs had no consistently significant effect on low- or high-frequency noise levels or on observer perception of signal quality.
authors.affiliation: Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA. kate.s.freeman@gmail.com
authors.forename: Kate S
authors.initials: KS
authors.lastname: Freeman
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Good
authors.forename: Philip H
authors.initials: PH
authors.lastname: Kass
authors.forename: Shin Ae
authors.initials: SA
authors.lastname: Park
authors.forename: Natalia
authors.initials: N
authors.lastname: Nestorowicz
authors.forename: Ron
authors.initials: R
authors.lastname: Ofri
mesh_terms: D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology; D018686:Anesthetics, Intravenous / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002077:Butorphanol / Q000008:administration & dosage / Q000494:pharmacology*; D020927:Dexmedetomidine / Q000008:administration & dosage / Q000494:pharmacology*; D004285:Dogs / Q000502:physiology*; D004359:Drug Therapy, Combination; D004596:Electroretinography / Q000662:veterinary*; D005260:Female; D007093:Imidazoles / Q000494:pharmacology
chemical_list: D058669:Adrenergic alpha-2 Receptor Antagonists; D018686:Anesthetics, Intravenous; D007093:Imidazoles; C050701:atipamezole; D020927:Dexmedetomidine; D002077:Butorphanol